I use the Transcend. It has a spongy thing in the tube near the pillows to capture humidity as you exhale. It then releases the moisture back on the inhale. It is better than no humidification but not as good as a full evaporation unit.
For a TPAC/TATL/TCON it is ok for a night.
The Transcend is a DC powered unit. I have their extended battery (Tks-insurance) and is no longer travelling with the Vegabound 110V inverted pack mentioned in an earlier post on a regular basis. I am now all DC with my travel needed devices.